WASHINGTON – The Food and Drug Administration says it is reviewing the safety of popular testosterone drugs for men in light of recent studies suggesting they can increase the risk of heart attack, stroke and death.

A study published earlier this week suggested testosterone therapy could double the risk of those problems in men older than 65. Another study published in November found that the hormone increased the risk by 30 per cent.

The FDA says it is evaluating information from those studies and others but hasn’t yet reached any conclusion.

The investigation comes amid an advertising blitz for testosterone gels, patches and injections marketed for low sex drive, fatigue and other age-related ailments in men.

U.S. prescriptions for testosterone have increased more than five-fold in recent years, with sales over $1.6 billion.